1. Technical Field
The present specification relates to a manufacturing method of a rotor core and a stator core that are able to be used in a rotary electric machine. More particularly, the present specification relates to a manufacturing method of a core for a rotary electric machine, in which a plurality of magnetic steel sheets are stacked and joined together.
2. Description of Related Art
A rotor core and a stator core used in a rotary electric machine such as an electric motor or a generator are manufactured by stacking a plurality of magnetic steel sheets and integrating them together to form a single unit. Also, the rotor core and the stator core are manufactured by, for example, stacking a plurality of laminated steel sheets flat, and joining adjacent magnetic steel sheets together by crimping.
That is, first, a crimped portion in which one surface side is a protruding portion and the other surface side is a recessed portion, is formed on a portion of the magnetic steel sheets. Then, the surface on the protruding portion side of the crimped portion of one magnetic steel sheet is placed facing the surface on the recessed portion side of the crimped portion of another magnetic steel sheet, and the two magnetic steel sheets are joined together by stacking them while fitting the protruding portion of the crimped portion of the one into the recessed portion of the crimped portion of the other.
For example, Japanese Patent Application Publication No. 2006-345657 (JP 2006-345657 A) describes a process of punching a magnetic steel sheet on which the crimped portion is already formed, and stacking the punched magnetic steel sheet together with another magnetic steel sheet that has already been punched and is held in a die. Also, when the magnetic steel sheet is being stacked, the recessed portion of the crimped portion of the punched magnetic steel sheet is fit together with the protruding portion of the crimped portion of the magnetic steel sheet held in the die, such that the two sheets are joined together. Also, as a punch, a punch is used in which a recessed portion is formed on a portion corresponding to the protruding portion of the crimped portion of the magnetic steel sheet. Using this punch enables the protruding portion of the crimped portion of the punched magnetic steel sheet to be inserted into the recessed portion of the other magnetic steel sheet that is held in the die, while supporting the area around the protruding portion of the crimped portion. As a result, the magnetic steel sheets are able to be stacked while being joined together, without deforming the magnetic steel sheets.
However, with the related art described above, there are cases in which the crimped portions that are formed beforehand on the two stacked magnetic steel sheets end up being out of position. That is, the protruding portion of one of the two stacked magnetic steel sheets is unable to suitably fit into the recessed portion of the other magnetic steel sheet. Therefore, the two stacked magnetic steel sheets may not be able to be suitably joined by the crimped portions.